Interest in operation to generate electrical power from direct current is extensive.
State of the art methods to derive rectangular waves to approximate sine waves from a direct current supply are disclosed within U.S. Pat. No. 5,642,275, U.S. Pat. No. 5,563,776 and U.S. Pat. No. 5,781,067. These teachings are devoid of generation of a pure sine wave
Well known methods employing differential amplifiers as voltage followers are divulged, for example, within U.S. Pat. No. 5,097,223, U.S. Pat. No. 4,928,059 and U.S. Pat. No. 4,506,230. Aforementioned disclosures are lacking of generation of a pure sixty Hertz sine wave from a direct current.
Overall, the prior art does not embody features of the present invention.
This invention relates to conversion of direct current to continuous alternating current from direct current, employing a differential operational amplifier.
Therefore, an object of this invention is to provide continuous alternating current.
A primary object of this invention is to provide a differential operational amplifier operated by direct current to provide continuous alternating current from direct current devoid of mechanical motion.
A major object of this invention is to provide continuous alternating voltage to become positive input to a differential operational amplifier.
A additional object of this invention is to derive continuous alternating current from the output of the differential operational amplifier.
A fundamental object of this invention is production of continuous alternating current from direct current provided from fuel cells.
An object of this invention is to arrange fuel cell terminals in series to establish direct current for application of a differential operational amplifier.
With the above and other objects in view, this invention relates to the novel features and alternatives and combinations presently described in the brief description of the invention.
A supply of direct current is converted to alternating current by a differential operational amplifier. The supply of direct current is frequently obtained from a stack of fuel cells. The stack of fuel cells consists of terminals connected in series to establish a direct current of adjacent positive and negative terminals, to thus provide direct current. The differential operational amplifier contains a positive input which is provided by an alternating current voltage. The positive input of alternating current develops alternating current by the differential operational amplifier operated as a voltage follower. Alternating current voltage applied on the positive input must be less than the direct current voltage to avoid clipping of the resulting alternating current by the differential operational amplifier. Developed alternating current is transported from the output of the differential operational amplifier with a transformer to establish voltage isolation by magnetic coupling. Voltage from the transformer provides feedback to the negative input of the differential operational amplifier. Magnetic coupling is generally combined with a secondary winding within a step-up transformer to increase voltage of the alternating current. Accordingly a feedback cycle has been accomplished and the supply of direct current is transformed into continuous alternating current without mechanical generation of alternating current. The differential operational amplifier is generally an integrated circuit and composed of field effect transistors selected from the group consisting of MOSFETS and JFETS including in individual or a combination thereof
Alternating current voltage applied on the positive input of the differential operational amplifier is a phase 120 degrees, relative to sinusoidal phase of 0 degrees, or a phase of 240 degrees to establish three phase current. Positive input of alternating current furnished to the differential operational amplifier is a sine wave frequency of sixty Hz or, alternately, fifty Hz.
The present invention, in its broadest aspect, is distinguished by producing alternating current from direct current, which comprises: a method claimed to produce alternating current from direct current, and providing a differential operational amplifier, and a supply of direct current. Alternating current voltage is applied to the positive input of the differential operational amplifier. A transformer is located on the output of the differential operational amplifier, for transporting alternating current, and establishing negative feedback to the negative input of the differential operational amplifier to form continuous alternating current whereby direct current provided to a differential operational amplifier is transformed to continuous alternating current.
Key features of this invention are:
Direct current from a fuel cell stack provides anode and cathode terminals, serially connected.
The terminals are of equal voltage of positive polarity and negative polarity.
The essential differential operational amplifier is supplied by direct current to establish continuous alternating current
Alternating current input to the non-inverting differential operational amplifier is supplied from an individual phase within a three phase configuration.
Magnetic coupling of the transformer is combined with a secondary winding within a step-up transformer to increase voltage of the alternating current.